Introduce min_heapify_all_eqaware() as a variant of min_heapify_all()
that uses the equality-aware version of sift_down, which is implemented
in a top-down manner.
This top-down sift_down reduces the number of comparisons from
O(log2(n)) to O(1) in cases where many elements have equal priority. It
enables more efficient heap construction when the heap contains a large
number of equal elements.
Cc: stable@xxxxxxxxxxxxxxx # 6.11+
Signed-off-by: Kuan-Wei Chiu <visitorckw@xxxxxxxxx>
---
include/linux/min_heap.h | 19 ++++++++++++++-----
lib/min_heap.c | 4 ++--
2 files changed, 16 insertions(+), 7 deletions(-)
diff --git a/include/linux/min_heap.h b/include/linux/min_heap.h
index 4cd8fd9db259..c2f6e1450505 100644
--- a/include/linux/min_heap.h
+++ b/include/linux/min_heap.h
@@ -371,17 +371,23 @@ void __min_heap_sift_up_inline(min_heap_char *heap, size_t elem_size, size_t idx
/* Floyd's approach to heapification that is O(nr). */
static __always_inline
void __min_heapify_all_inline(min_heap_char *heap, size_t elem_size,
- const struct min_heap_callbacks *func, void *args)
+ const struct min_heap_callbacks *func, void *args, bool eqaware)
{
ssize_t i;
+ siftdown_fn_t sift_down = eqaware ? __min_heap_sift_down_eqaware_inline :
+ __min_heap_sift_down_inline;
for (i = heap->nr / 2 - 1; i >= 0; i--)
- __min_heap_sift_down_inline(heap, i, elem_size, func, args);
+ sift_down(heap, i, elem_size, func, args);
}
#define min_heapify_all_inline(_heap, _func, _args) \
__min_heapify_all_inline(container_of(&(_heap)->nr, min_heap_char, nr), \
- __minheap_obj_size(_heap), _func, _args)
+ __minheap_obj_size(_heap), _func, _args, false)
+
+#define min_heapify_all_eqaware_inline(_heap, _func, _args) \
+ __min_heapify_all_inline(container_of(&(_heap)->nr, min_heap_char, nr), \
+ __minheap_obj_size(_heap), _func, _args, true)
/* Remove minimum element from the heap, O(log2(nr)). */
static __always_inline
@@ -487,7 +493,7 @@ void __min_heap_sift_down_eqaware(min_heap_char *heap, size_t pos, size_t elem_s
void __min_heap_sift_up(min_heap_char *heap, size_t elem_size, size_t idx,
const struct min_heap_callbacks *func, void *args);
void __min_heapify_all(min_heap_char *heap, size_t elem_size,
- const struct min_heap_callbacks *func, void *args);
+ const struct min_heap_callbacks *func, void *args, bool eqaware);
bool __min_heap_pop(min_heap_char *heap, size_t elem_size,
const struct min_heap_callbacks *func, void *args);
void __min_heap_pop_push(min_heap_char *heap, const void *element, size_t elem_size,
@@ -514,7 +520,10 @@ bool __min_heap_del(min_heap_char *heap, size_t elem_size, size_t idx,
__minheap_obj_size(_heap), _idx, _func, _args)
#define min_heapify_all(_heap, _func, _args) \
__min_heapify_all(container_of(&(_heap)->nr, min_heap_char, nr), \
- __minheap_obj_size(_heap), _func, _args)
+ __minheap_obj_size(_heap), _func, _args, false)
+#define min_heapify_all_eqaware(_heap, _func, _args) \
+ __min_heapify_all(container_of(&(_heap)->nr, min_heap_char, nr), \
+ __minheap_obj_size(_heap), _func, _args, true)
#define min_heap_pop(_heap, _func, _args) \
__min_heap_pop(container_of(&(_heap)->nr, min_heap_char, nr), \
__minheap_obj_size(_heap), _func, _args)
diff --git a/lib/min_heap.c b/lib/min_heap.c
index 2225f40d0d7a..a422cfaff196 100644
--- a/lib/min_heap.c
+++ b/lib/min_heap.c
@@ -42,9 +42,9 @@ void __min_heap_sift_up(min_heap_char *heap, size_t elem_size, size_t idx,
EXPORT_SYMBOL(__min_heap_sift_up);
void __min_heapify_all(min_heap_char *heap, size_t elem_size,
- const struct min_heap_callbacks *func, void *args)
+ const struct min_heap_callbacks *func, void *args, bool eqaware)
{
- __min_heapify_all_inline(heap, elem_size, func, args);
+ __min_heapify_all_inline(heap, elem_size, func, args, eqaware);
}
EXPORT_SYMBOL(__min_heapify_all);
--
2.34.1
